我們對分子磁鐵[FeII(Δ)FeII(Λ)(ox)2(Phen)2]n（其單位分子式為C28H16Fe2N4O8）進行了磁性量測、中子繞射、以及低溫比熱等實驗。 在磁性研究上，當溫度在大於轉變溫度Tm（8.6 K）的範圍時，我們發現樣品的磁性符合短程有序的一維鏈狀結構的陶鐵磁行為，並可以用擁有交替的Landé因子的一維鏈狀結構模型來解釋。然而，在溫度小於Tm時，因為鏈與鏈之間交互作用力的增強，我們發現長程磁有序的產生。另外，由中子繞射實驗我們確定了此樣品在8.6 K處長程磁有序的產生，以及在磁有序溫度下之磁結構。低溫比熱的量測也證實了在8.6 K時產生長程磁有序。另外也發現了在更低溫處可能由晶體內場造成的零磁場分裂。

The molecular magnet [FeII(Δ)FeII(Λ)(ox)2(Phen)2]n, whose chemical formula is C28H16Fe2N4O8 for unity, has been studied by magnetization measurements, neutron diffraction, and field-dependent specific heat. From the magnetization measurements, the quasi-ferrimagnetic behavior at T>Tm region can be well described with alternating Land&eacute; factors within 1D Ising chain model. However, in T<Tm region, the construction of long-range magnetic ordering due to the increase of interchain interaction was investigated, which is consistent with the anomaly shown in the low temperature specific heat measurement. Furthermore, an intrinsic antiferromagnetic configuration is deduced from analyzing Bragg pattern of neutron scattering. In specific heat measurement, a λ-type anomaly indicating the long-range magnetic ordering was observed. In addition, the magnetic entropy due to this anomaly is much smaller than expected value indicating the spin fluctuated as short-range ordering at T>Tm.

Abstract 1
論文摘要 2
Contents 3
List of Figures 5
List of Tables 7
Chapter 1: Introduction 8
1.1 Single-Molecule Magnets (SMMs) 8
1.2 Single-Chain Magnets (SCMs) 10
1.3 Our Work: [FeII(D)FeII(L)(ox)2(Phen)2]n 10
Chapter 2: Theory 13
2.1 One Dimensional Ferrimagnetic Chain with Alternating Land&eacute; Factors 13
2.2 Magnetic Quantum Tunneling 17
2.3 Neutron Diffraction 21
2.3.1 Neutron Nuclear Diffraction 21
2.3.2 Neutron Magnetic Diffraction 22
2.4 Specific Heat 23
2.4.1 Debye Lattice Heat Capacity 23
Chapter 3: Experiment Details 26
3.1 Sample Preparation: [FeII(D)FeII(L)(ox)2(Phen)2]n 26
3.2 Magnetic Properties Measurement 26
3.2.1 DC Magnetic Susceptibility 27
3.2.2 AC Magnetic Susceptibility 27
3.2.3 Isotropic Field-Dependent Magnetization 27
3.3 Neutron Diffraction 31
3.3.1 Neutron Nuclear Diffraction 31
3.3.2 Neutron Magnetic Diffraction 31
3.4 Low Temperature Specific Heat 34
3.4.1 Principle of Operation 34
3.4.2 The Instrument 37
3.4.3 Measure Process 38
Chapter 4: Results and Discussion 45
4.1 The Structure of [FeII(D)FeII(L)(ox)2(Phen)2]n 45
4.2 Magnetic Properties 49
4.2.1 DC Susceptibility 49
4.2.2 AC Susceptibility 57
4.2.3 Magnetic Hysteresis Loop 59
4.3 Neutron Diffraction 61
4.3.1 Neutron Nuclear Diffraction 61
4.3.2 Neutron Magnetic diffraction 63
4.4 Low Temperature Specific Heat 68
Chapter 5: Conclusion 75
Reference 76

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